The invention relates generally to refueling apparatus for transportation vehicles or other devices fueled by low pressure natural gas or other gaseous hydrocarbon fuels. More particularly, the invention relates to such refueling apparatus employing high-surface-area sorbent (adsorbent and/or absorbent) materials for filtering the gaseous fuel, for storing a quantity of the gaseous fuel, or both, and preferably employing hermetically-sealed gas compressor apparatus for pressurizing the gaseous fuel to a desired pressure.
Over the years, concerns have developed over the availability of conventional fuels (such as gasoline or diesel fuel) for internal combustion engine vehicles, the operating costs and fuel efficiencies of such vehicles, and the potentially adverse effects of vehicle emissions on the environment. Because of such concern, much emphasis has been placed on the development of alternative to such conventional vehicle fuels. One area of such emphasis has been the development of vehicles fueled by natural gas or other methane-type gaseous fuels, either as the sole fuel or as one fuel in a dual-fuel system. As a result, vehicles using such fuels have been produced and are currently in use on a relatively limited basis both domestically and abroad.
In order to provide such gaseous fueled vehicles with a reasonable range of travel between refuelings, it has previously been necessary to store the on-board gaseous fuel at very high pressures, generally in the range of approximately 2000 psig (13.9 MPa) to 3000 psig (20.7 MPa). Without such high-pressure on-board storage, the practical storage capacity of such vehicles was limited because of space and weight factors to the energy equivalent of approximately one to five gallons (3.7 to 19 liters) of conventional gasoline. Thus, by compressing the gaseous fuel to such high pressures, the on-board storage capacities of such vehicles were increased.
One disadvantage of the compressed gaseous fuel systems discussed above is that they require complex and comparatively expensive refueling apparatus in order to compress the fuel to such high pressures. Such refueling apparatus has therefore been found to effectively preclude refueling the vehicle from a user's residential natural gas supply system as being commercially impractical. Furthermore, such high pressure apparatus is frequently perceived by the public as being more dangerous than low pressure apparatus. For example, the public is already accustomed to refrigerant pressures in the area of approximately 200 psig (1380 KPa) in home refrigeration units and does not find such low pressures objectionable.
Another alternative to the above-discussed fuel storage and vehicle range problems, has been to store the on-board fuel in a liquid state generally at or near atmospheric pressure in order to allow sufficient quantities of fuel to be carried on board the vehicles to provide reasonable travel ranges between refuelings. Such liquified gas storage has also, however, been found to be disadvantageous because it requires inordinately complex and comparatively expensive cryogenic equipment, both on board the vehicle and in the refueling station, in order to establish and maintain the necessary low gas temperatures.
In non-vehicular gaseous fuel storage applications for stationary installations, it has been found that the use of high-surface-area adsorptive materials has provided for significantly increased storage capacities at relatively low pressures. Such adsorptive materials typically include zeolites, activated carbons, silica gels, and various clays, for example. For example, U.S. Pat. No. 2,712,730, issued to Spangler on July 12, 1955, discloses a method and apparatus for storing various types of (liquified) hydrocarbon gases which utilizes an adsorbent in order to increase the storage capacity of the stationary system. However, in spite of significant and extensive research and development efforts in the area of gaseous fuel powered vehicles, no natural gas fuel storage or refueling systems have emerged that apply sorbent storage technology to on-board vehicular storage and to their refueling apparatus. In fact, the above-discussed compressed natural gas and liquefied natural gas systems have been generally regarded as the only two feasible systems for natural gas powered vehicle applications.
The need has thus arisen for a gaseous fuel powered vehicle that is capable of storing reasonable quantities of on-board fuel storage at relatively low pressures, and for practical and comparatively inexpensive refueling apparatus allowing such a vehicle to be refueled by the user from a residential natural gas supply system.
In accordance with the present invention, an apparatus for supplying fuel to a gaseous fuel consuming device, such as a vehicle, a lawn mower, or a snow thrower, for example, is adapted to be connected in fluid communication with a source of gaseous fuel and generally includes means for compressing the fuel in order to increase its pressure to a predetermined value, cooling means for reducing the temperature of the compressed gaseous fuel, and discharge means adapted to be releasably connected to the gaseous fuel consuming device. Preferably, the gaseous fuel supply apparatus also includes sorbent filter means for substantially removing impurities and certain predetermined fuel constituents from the fuel, sorbent storage means for sorptively storing a quantity of the previously compressed gaseous fuel, and automatic control apparatus for allowing the compressed gaseous fuel to be supplied to the fuel consuming device through the discharge means either from the sorbent storage means or from the compressor means by bypassing the storage means, if such storage means is included. As referred to herein, the terms "sorbent" and "sorptive" are intended to refer to both adsorbing or absorbing, or both.
In the preferred embodiment, the pressure of the compressed gaseous fuel supplied to the fuel consuming device is generally in the range of approximately 200 psig to approximately 400 psig (1380 KPa). Furthermore, the compressor means preferably comprises one or more hermetically-sealed gas compressors for compressing gaseous fuel to such pressures, the compressors preferably being generally of the type of gas compressors commonly found in refrigeration equipment.
One of the primary objectives of the present invention is to provide a refueling apparatus that may be manufactured significantly less expensively than those of the prior art in a compact, modular form, and that is adapted to be connected to a user's residential natural gas or other gaseous fuel supply system. Another of the primary objectives of the present invention is to provide such an apparatus that can be conveniently, safely, and relatively inexpensively operated and used by the consumer.
A vehicle of the type referred to herein is disclosed and described in a patent application entitled GASEOUS HYDROCARBON FUEL STORAGE SYSTEM AND POWER PLANT FOR VEHICLES. Such vehicle and the exemplary refueling apparatus herein are also disclosed in a patent application entitled GASEOUS HYDROCARBON FUEL STORAGE SYSTEM AND POWER PLANT FOR VEHICLES AND ASSOCIATED REFUELING APPARATUS. Both of said applications, which are incorporated by reference herein, are assigned to the same assignee as the present application and are filed of even date.
Additional objectives, advantages and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.